[asterisk-users] Mobiles not detecting as BUSY until Dial() timeout completes

[A J Stiles]

I'm not sure if this is an Asterisk thing, a handset thing or a telco thing, 
so please be gentle with me if this is not the right place to ask .....

When placing a call over a SIP channel to a mobile phone, if the phone is 
engaged, it does not return a BUSY status straightaway.  Rather, I get a 
ringing-out tone for the timeout duration specified in the Dial() statement; 
*then* I get ${DIALSTATUS}=BUSY.

Now, given how far we have moved on since the days of clicky-clicky exchanges, 
it is entirely possible that the mobile phone implicitly supports multiple 
"lines", so you can put an existing caller on hold, talk to the new caller and 
then switch between them as long as they stay on the line .....  in which 
case, this behaviour is pretty much what should be expected -- Asterisk 
doesn't know for sure that the remote party really is engaged, because they 
retain the option to put their call on hold and answer you, so it lets the 
timeout run; then, since they were already on a call at the time the first 
signalling message was sent, it sets the dialstatus to BUSY.


Where should I be looking, if I want to reproduce the "old-fashioned" 
behaviour and return an engaged signal straight away?

-- 
AJS

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